1. Technical Field
The present disclosure relates to an imaging optical lens system, imaging device and mobile terminal. More particularly, the present disclosure relates to a compact imaging optical lens system and imaging device applicable to a mobile terminal.
2. Description of Related Art
In recent years, with the popularity of mobile terminals having camera functionalities, the demand of miniaturized optical systems has been increasing. As the advanced semiconductor manufacturing technologies have allowed the pixel size of sensors to be reduced and compact optical systems have gradually evolved toward the field of higher megapixels, there is an increasing demand for compact optical systems featuring better image quality.
A conventional optical system employed in a portable electronic product mainly adopts a four-element lens structure. Due to the popularity of mobile terminals with high-end specifications, such as smart phones, tablet personal computers and wearable apparatus, the requirements for high resolution and image quality of present compact optical systems increase significantly. The conventional optical systems cannot satisfy these requirements of the compact optical systems.
Although other conventional optical systems with five-element lens structure enhance image quality, these are not favorable for correcting Petzval Sum. Moreover, it tends to produce excessive aberration in a peripheral region of an image which might cause vagueness and distortion in the peripheral region of the image.
In light of the foregoing, a need exists in the art for having an optical system favorable for effectively correcting the Petzval Sum. In addition, it might be favorable for reducing the aberration in the peripheral region of the system through adjusting the curvatureness of the image-side surface of the fourth lens element in order to avoid vagueness and distortion in the peripheral region